Automatic vehicle leveling system with electronic time delay

ABSTRACT

In preferred form, a fully automatic electrically operated leveling system for a vehicle having an undamped height sensing electric switch on one of a pair of air springs that operates to indicate vehicle height. An electric motor driven air compressor and electronic control circuit are mounted as a unit in a sealed storage tank along with a solenoid operated valve. The air compressor exhausts air from the springs into the tank to lower the vehicle chassis when it is unloaded. The solenoid operated valve directs air from the tank to the springs to raise the vehicle chassis when it is loaded. The electronic control circuit includes time delay means to prevent energization of the motor or solenoid in response to normal road movements of the vehicle.

United States Patent AUTOMATIC VEHICLE LEVELING SYSTEM WITH ELECTRONICTIME DELAY 5 Claims, 7 Drawing Figs.

U.S. Cl 267/65 D, 280/l24 F, 280/6 R Int. Cl B60 11/26 Field of 267/65D;

[56] References Cited UNITED STATES PATENTS 2,828,139 3/ I958Lantzenhiser 267/65 D Primary Examiner-Philip Goodman Attorneys-W. S.Pettigrew and J. C. Evans ABSTRACT: In preferred form, a fully automaticelectrically operated leveling system for a vehicle having an undampedheight sensing electric switch on one of a pair of air springs thatoperates to indicate vehicle height. An electric motor driven aircompressor and electronic control circuit are mounted as a unit in asealed storage tank along with a solenoid operated valve. The aircompressor exhausts air from the springs into the tank to lower thevehicle chassis when it is unloaded. The solenoid operated valve directsair from the tank to the springs to raise the vehicle chassis when it isloaded. The electronic control circuit includes time delay means toprevent energization of the motor or solenoid in response to normal roadmovements of the vehicle.

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& ,4 X 1 W kg 76 Q MbYZFfi 6 George Ll). Jadrson ATTORNEY AUTOMATICVEHICLE LEVELING SYSTEM WITH ELECTRONIC TIME DELAY This inventionrelates to fully automatic electrically operated, leveling systems for avehicle and more particularly to a system of this type having first andsecond electrically energizable components for controlling exhaust andinflation of a fluid spring in the system.

In automatic level controls for vehicles it is desirable to have an allelectric powered, automatic leveling system which will maintain the rearaxle to chassis separation of the vehicle within a set range as weightis added or removed from the pas senger compartment or trunk of thevehicle.

In such systems the axle to chassis separation varies directly withapplied load which causes the length of the primary load supportingspring of the suspension to be reduced. Height correction of changes inthe axle to chassis separation may be produced by means that willintroduce or exhaust a predetermined amount of pressurized fluid into orfrom rear located auxiliary load supporting fluid springs to raise orlower the rear of the vehicle chassis as required.

The electrical controller of such leveling systems desirably shouldoperate independently of changes in riding height that occur duringnormal vehicular maneuver such as stopping, accelerating, climbinggrades, or traveling curves, corners or uneven roads. These maneuvershenceforth being characterized as normal road movements.

Furthermore, the electrical controller should be one that is able toaccurately maintain a predetermined height relationship between thesprung mass of the vehicle, represented by the vehicle chassis, and itsunsprung mass, represented by the rear axle assembly when connected to avariable power source from to volts such as is produced by a 12 voltdirect current battery of a vehicle. The controller should be one thatis able to handle as high as 28 amperes of compressor motor currentduring startup.

Furthermore, it is desirable to include a low cost double pole doublethrow undamped switch for sensing the height of the vehicle and toprovide an equally low cost electronic circuit in association therewithfor providing a predetermined time period delay before any of theelectrical control components of the leveling system are operatedthereby to isolate the system from ordinary road movements of the typeset forth above.

Moreover, in such systems it is desirable to arrange the electric motordriven compressor and solenoid operated valve in a compact unitaryprechargeable package that is easily located in a limited amount ofspace within the engine compartment at a point accessible from under thehood.

An object of the present invention is to improve vehicle levelingsystems by the provision therein of an electric motor controllerincluding a relay operated switch having an energizable coil, anundampened height sensing switch for electrically connecting the coil toa power source and a static amplifier connected to the coil andcontrolled by timer means to be conductive following a predeterminedroad movement dampening time period to complete a current path throughthe coil for energizing the motor only in response to sustained vehicleload changes.

Still another object of the present invention is to provide an improvedvehicle leveling system having an electronic module which includes delaymeans for association with first and second height controllingelectrical components of the system to delay operation of the componentsfor a predetermined time period when an undamped electrical switchdetects vehicle body moves above and below a predetermined height inresponse to normal road movements.

Another object of the present invention is to provide an improvedautomatically controlled, electrically powered leveling system forchanging the pressure within an auxiliary load supporting fluid springwherein the system includes a pressurized tank enclosing an electricmotor driven compressor for pumping down the fluid springs to reduce theload bearing capacity thereof and wherein a compact combination electriccontrol circuit and solenoid operated valve assembly is supported withinthe tank and operative to direct high-pressure fluid from the tank tothe fluid springs to increase the load carrying capacity thereof; anundamped height sensor switch detects whether the vehicle body is aboveor below a predetermined control height and conditions the controlcircuit for selectively operating the electrical components to maintainthe control height.

Still another object of the present invention is to provide an improvedall electric automatically controlled vehicle leveling system of thetype including auxiliary load carrying fluid springs having the pressurelevel therein controlled by flow of pressurized fluid through a commonexhaust and supply conduit connected to the fluid springs by theprovision of combination valve control unit fit within a sealed storagetank having an electrically motor driven compressor therein dischargingdirectly into the tank for pressurizing it and wherein the compressorhas its inlet in communication with the conduit through a one way checkvalve for pumping down the fluid springs and wherein the valve controlunit includes a solenoid operated valve selectively energized when thevehicle body is below a predetermined height to communicate the interiorof the tank with the fluid springs for increasing the load carryingcapacity thereof.

Still another object of the present invention is to provide an improvedall electrically automatically controlled leveling system that has anelectrically motor driven compressor within a pressurized tank and anelectric solenoid operated valve and an electronic control circuit thatare in a package sealed within the tank for regulating flow through afirst pmageway into a common conduit from the valve assembly to thefluid spring means and wherein the package includes a second passagewayto the common conduit that is controlled by a one way check valve thatprevents backflow of fluid from the pressurized tank through thecompressor to the common conduit and serves as a path for flow of fluidto the compresor during a pumpdown phase of operation.

These and other objects are attained in one working embodiment of theinvention in a system that includes two spaced apart auxiliary loadsupporting combination shock absorber and air spring units each havingtheir top and bottom mounts adapted to be connected respectively betweenthe lower frame of the vehicle body and the rear axle housing of therear suspension of the vehicle. The system includes a double pole,double throw switch that is strapped on one side of one of the units tosense the height relationship between the top of the shock absorber anda surrounding dust shield portion of the shock absorber which in turnrepresents the height relationship between the vehicle body and the axlehousing.

When the vehicle body is above a desired height relationship the switchis in a first position wherein an electric motor is energized to pumpdown both of the auxiliary load carrying air springs on the combinationunit and to increase the pressure within a storage tank. When thevehicle body is below the desired height relationship the switch ispositioned to energize a solenoid valve for connecting the presurizedtank with the air spring means to increase the presure level therein; toraise its load supporting capacity; to return the vehicle body to adesired height relationship with the axle housing.

The switch is an undamped mechanism that electrically connects first andsecond electrical components in the system to the positive terminal ofthe vehicle battery. An electronic control module receives a signal fromthe switch each time it connects one or the other of the components tothe battery to charge a timing circuit that delays energization of astatic amplifier that powers the electrical components in the system.

The time delay is selected to prevent operation of the electricalcomponents in response to ordinary vehicle road movements.

A switching transistor is turned on each time one of the components isconnected to the power supply to complete the timing circuit. When theundampened switch on the air spring is turned off the switchingtransistor is turned off and the tim ing circuit is reset. Thus, only asustained load change that maintains the undamped height sensor switchcontinuously closed will cause the timing circuit to condition thestatic amplifier conductive thereby to energize one of the other of thecomponents to produce a change in the pressure level of the air springsfor leveling.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

FIG. I is a diagrammatic view ofa leveling system including the presentinvention;

FIG. 2 is an enlarged view in vertical section taken along the line 22of FIG. 3 looking in the direction of the arrows;

FIG. 3 is a view in top elevation of a valve and electronic controllerassembly in the present invention;

FIG. 4 is a vertical sectional view taken along the line 4-4 of FIG. 3looking in the direction of the arrows;

FIG. 5 is an enlarged vertical sectional view of the valving componentsof the assembly in FIG. 2; and

FIG. 6 is an enlarged horizontal sectional view taken along the line 6-6of FIG. I looking in the direction of the arrows;

FIG. 7 is an electric circuit diagram of a control system for regulatingthe electrical components in the system of FIG. 1.

Referring now to the drawings, in FIG. 1 a fully automatic electricclosed loop vehicle leveling system 10 is illustrated. It includes apair of combination shock absorber and air spring units 12, I4 each ofwhich includes a top end mount assembly I6 and a bottom end mountassembly 18. The top end mount assembly 16 is adapted to be connected tothe bottom frame of a vehicle body which represents a sprung mass. Thebottom end mount I8 is adapted to be connected to a portion of the rearsuspension assembly, for example, the rear axle housing which representsan unsprung mass in the system.

Both of the units I2, I4 represent an auxiliary load supporting devicethat is associated with a primary load supporting spring that maintainsa predetermined curb height between the vehicle body and the axlehousing when the vehicle is un' loaded.

In order to maintain this predetermined curb height or any otherpredetermined height relationship, the vehicle leveling system 10 isoperated to vary the pressure in a variable volume pressurizable fluidchamber 20 of each unit 12, I4 formed between a dust tube 22 closed atits upper end by a cap 24 and an outer cylinder 25 of a shock absorber26.

In the illustrated arrangement the shock absorber 26 also includes apiston rod 28 that moves exteriorly of the cylinder 25.

The chamber 20 is closed by a flexible sleeve 30 that has one endthereof fastened to the open lower end of the dust tube 22 by a clampring 32 and the opposite end thereof secured to the outer periphery ofthe cylinder 25 by a clamp ring 34.

The chamber 20 of the unit 14 has an inlet fitting 36 thereon and anoutlet fitting 38 that is joined by a crossover tube 40 to an inletfitting 42 to the chamber 20 of the unit 12. A common exhaust and supplyconduit 44 has one end thereof connected to the inlet fitting 36 and theopposite end thereof connected to a fitting 46 on a combination valveand fluid supply assembly 48.

In the illustrated arrangement the assembly 48 includes a housing 50that is supported in an opening 52 of a pressurized storage tank 54.

An electric compressor drive motor 56 is supported within the tank 54 bysprings 57. It drives an air compressor 58 having an inlet 60 and anoutlet 62.

The outlet 62, more particularly, is in direct communication with theinterior of tank 54 and the inlet 60 is connected to one end of a springreinforced suction tube 64 that has the opposite end thereof connectedto a tube member 66 depending from the housing 50.

ln the illustrated arrangement the electrical drive motor 56 iscontrolled by a relay operated switch 68 that is supported on one sideof a circuit board 70 along with an electronic control module 72 to bedescribed.

The relay 68 constitutes a first electrically energizsble component forcontrolling the operation of the leveling system I0.

Additionally, the system includes a solenoid operated valve 74 whichcommunicates the tank 54 with the conduit 44 when a coil 76 thereof isenergized.

The coil 76 constitutes a second electrically energizable component forregulating the operation of the leveling system 10.

The system 10 further includes a height sensor switch 78 that is held onone side of the unit l4 by a strap 89 to locate a cam operator 82 inspring biased relationship with the top closure 84 of the shock absorbercylinder 25 of unit 14 to position a contact carrying movable spring arm86 with respect to a first pair of motor contacts 88 and a second pairof solenoid contacts 90 both of which are maintained normally open andare bridged when the movable spring arm 86 has spaced apart contacts 92,93 thereon in engagement with one or the other of said motor or solenoidcontacts 88, 90.

The height sensor switch 78 is a low cost nondamped unit that senseseach relative movement of the dust tube 22 with respect to the shockabsorber cylinder 26 which reflects normal road movements between thesprung and unsprung mass of the vehicle.

Referring now more particularly to the combination valve and fluidsupply assembly 48, as seen in FIG. 2, the housing 50 thereof includes ahead portion 94 located exteriorly of the tank 54. It includes anannular groove 96 having an O-ring seal 98 thereon that is held insealing engagement with a flat outer surface portion of the tank I00around the opening 52 therein.

More particularly, the unit includes a plurality of weld bolts 102 onthe tank I00 that extend through the head portion 94 at the comersthereof and threadably receive nuts 104 on the threaded ends thereof tosealingly press the O-ring 98 against the surface to prevent leakagebetween the housing 50 and the tank 54 around the opening 50 therein.

The fitting 46 more particularly shown in FIG. 5, includes a nut 106which is threaded into a tapped opening I08 in communication with acrossover passageway III).

The common exhaust and supply conduit 44 has one end I12 thereindirected through the nut I06 and into a tubular resilient sealingelement II4 which is held in sealing engagement with the outer peripheryof the tube II2 by a deformed metal ferrule I16 that has the noseportion II8 thereof deformed radially inwardly of the outer surface ofthe tube 112 for holding it in place within the fitting 46.

In order to precharge the tank 54 the housing portion 94 furtherincludes an inlet passageway I20 that is located in spaced parallelismwith the crossover passage as is shown in FIG. 4. The passageway I20 hasa valve I22 threadably supported therein which includes a movable stemI24 biased by spring means (not shown) in a direction to move a valvingelement 126 into sealed engagement with a seat I28.

A threaded plug 130 with a knurled head 132 is threadably received in atapped opening 134 when the tank has been precharged. It includes a stem136 with an annular O-ring I38 supported in a groove therein to seal theinlet passageway I20 and to prevent inadvertent operation of thecharging valve I22.

When the plug I30 is removed a charge fitting can be inserted into thetapped opening 134 to cause the stem 124 to be depressed thereby toallow flow of pressurized fluid through the inlet opening I20 which hasa 90 offset extension I40 therein which communicates with the tankinterior through the base of the housing 50.

Referring now more particularly to FIG. 5 the solenoid operated valve 74is illustrated as including an outer housing I42 which protects the coil76. The coil has a central opening I44 therethrough in which is centeredan elongated armature stem I46 that is supportingly received within asleeve bearing I48 located in spaced relationship to the inner peripheryof the coil 76 to define an annular flow passageway [50 therebetween.

n the upper end of the sleeve 148 is supported one end of a coil spring152 that has the opposite end thereof in engagement with the undersideof a head portion 154 of the armature. On the upper face of the head 154is supported a circular valving element 156 that is biased by the spring152 into sealing engagement with a seat 158 formed on the underside of avalve insert 160 having a passageway 162 therethrough in communicationwith the crossover passageway 110 thence to the conduit 44.

On one side of the housing is an elongated depending tubular extension164 which has a tubular fitting 166 therein held in place by a supportplate 168 that fits in and around a groove 170 in the tubular fitting166 to hold it within an outlet passageway 172 through the extension164.

The lower end of the tubular fitting 166 includes a plurality ofcircumferential ribs 174 thereon that interlock within one end of theinlet or section conduit 64 as seen in FIG. 2. A groove 176 in theinsert 166 supports an O-ring seal 178 that sealingly engages the insidewall of the extension 164 to seal the passageway 172 as fluid flowstherefrom into an opening 180 in the insert 166.

Backflow through the suction conduit 64 is blocked by means including acoil spring 182 that has one end thereof supportingly received on an endshoulder 184 on the insert 166 and the opposite end thereof supportinglyreceived by a guide boss 186 on a valving element 188. It has an upperface 190 thereon normally spring biased closed against a valve seat 192around housing passageway 194 as is best seen in FIG. 5.

In accordance with certain principles of the present invention theelectronic control module 72 includes means for producing apredetermined time delay in the system to prevent operation of thesystem by normal road movements of the vehicle. Additionally, the module72 includes means that constitute a controller for the motor 56 toenergize it following periods when the vehicle is unloaded thereby tocause the auxiliary load supporting devices 12, 14 to be pumped down tolevel the vehicle.

A further feature is that the module 72 includes means for controllingthe electrical solenoid to be operative following a sustained additionof load to the vehicle to pump up or pressurize the auxiliary loadsupporting devices l2, 14 to correct for spring compression that wouldlocate the chassis of the vehicle below a predetermined heightrelationship with respect to an unsprung mass portion of the vehicle.When the solenoid operated valve 74 is energized it directs apredetermined amount of air from the interior of the pressurized tank 54into the variable volume pressurizable chambers 20 of the devices l2,14.

The module 72 is more particularly set forth in the control circuit ofFIG. 7 which is illustrated as including a DC battery 191, for example,a 12 volt rated vehicle battery. Additionally, the circuit includes anignition switch 193 and the double pole double throw switch 195 operatedby the height sensor 78 on the side of the device 10.

The circuit includes a first power circuit for control of the motorincluding a conductor 197 connected to the positive terminal of thebattery 193 and a conductor 198 electrically connected to one tenninalof a normally open switch 199. The other terminal thereof iselectrically connected by a conductor 201 to one side of a motor relaycoil 200 that has the opposite side thereof electrically connected by aconductor 202 thence through a conductor 204 to the anode terminal of asolid state switching device 206 that is maintained normally off. Whendevice 206 is electrically conductive the coil circuit is completedthrough a conductor 208 to ground.

Additionally, the circuit includes a solenoid power circuit fromconductor 197 thence through a conductor 210 to the ignition switch 193thence through a conductor 212 to one terminal of a second normally openswitch 214 that has the other terminal thereof connected by a conductor216 to one side of a solenoid valve coil 76.

The opposite side of the coil 76 is connected by a conductor 220 to thepreviously described portion of the electrical circuit through the solidstate switching device 206 thence to ground.

The solid state switching device 206 is under the control of a timingcircuit that is electrically connected to both of the aforementionedpower circuits under the control of the height sensor 190.

The timing circuit more particularly includes, in the case of the motorpower circuit, a conductor 222 from conductor 201 which is connected toa diode 224 which in turn is electrically connected to a resistor 226thence to the negative terminal of a capacitor 228. Additionally, aconductor 230 electrically connects the base or control terminal of thesolid state switching device 206 to the RC timing circuit represented bythe resistance 226 and the capacitor 228.

The RC circuit is completed from the positive terminal of the capacitor228 through a NPN reset transistor 232 that has its emitter electricallyconnected by a conductor 234 to conductor 208 to ground.

In the case of the solenoid coil circuit the timing circuit isconstituted by a conductor 236 that is electrically connected to oneside of a diode 238 which has its opposite side electrically connectedby a crossover conductor 240 to the aforementioned RC timing circuitincluding the resistor 226, the capacitor 228 and the normally closedreset transistor 232.

Additionally, the control circuit includes a signal circuit to thetransistor 232 which is energized if either of the aforementioned motorpower or solenoid power circuits are completed by the height sensorswitch 78. More particularly it includes a conductor 242 electricallyconnecting the crossover conductor 240 to one side of a resistor 244which has the opposite side thereof electrically connected by aconductor 246 to the base of the transistor 232. A resistor 248electrically connects the base-emitter junction of the transistor 232 tothe conductor 208 to ground.

In addition, the circuit includes a continuously energized circuit fromthe positive terminal of the battery 191 to a conductor 250 which iselectrically connected by conductor 252 to one contact of a relayoperated motor control switch 254 which has the other contact thereofelectrically connected by a conductor 256 to one side of the electricdrive motor 56 which has the opposite side thereof electricallyconnected by conductor 258 to ground.

Additionally, the conductor 250 is electrically connected to one end ofa resistor 260 which in turn is electrically connected by conductor 262to a junction between the positive terminal of the capacitor 228 and thecollector of the transistor 232.

Operation of the system produces a signal when the vehicle is ridingabove or below a predetermined normal riding level from the positiveterminal of the battery 191 through height sensor 78 thence througheither the power circuit of the motor relay coil or that of the solenoidcoil to the RC timing circuit. Furthermore, the circuit includes meansto operate either the solenoid valve or the compressor in response to acontinued vehicle riding height signal representing a change in loadingof the vehicle.

Under a no signal condition when the vehicle is level and the movablecontact of the sensor 78 is positioned in open relationship with respectto both the switch 199 and the switch 214, the transistor 232 is turnedoff thereby acting as an open switch to ground. The capacitor 228 duringthis period. is charged through conductor 250, the resistance 260 to thepositive terminal of the capacitor. The level of charge on the positiveterminal of the capacitor 228 will equal that of the voltage of thebattery 186 which can, even with a 12 volt rated battery, vary in arange from 10 to 15 volts depending upon the condition of the battery ata particular time.

When either the switch 199 in the motor power circuit or the switch 214in the solenoid power circuit is closed. the transistor 232 isimmediately turned by a current applied to its base from either of thepower circuits. This completes the above-defined capacitor chargingcircuit.

At this point in the system operation, the capacitor voltage at the baseof the Darlington pair 206 is now a negative voltage with reference toground an amount equal to the battery voltage.

Additionally, the capacitor 228 is connected to ground through thetransistor 232. The capacitor charges in the opposite direction fromthis minus battery voltage to approximately 1 volt positive. When acertain predetermined positive voltage is reached, this is a basecurrent flow which turns on the Darlington pair 206. The amplifierbegins to conduct from its anode to its cathode terminal and provides acurrent path to ground for either the relay coil 200 or solenoid coil218. The delay time is measured from the time the signal turns on thetransistor 232 to the time that the Darlington amplifier 206 isconductive.

The charging time of the capacitor 228 is controlled by resistor 226which is large with respect to the other resistors in the network. Whenthe sensor switch 78 has its switches I99, 214 opened, the transistor232 immediately shuts off. The resistor 260 is relatively small comparedto the resistor 226 and the capacitor 228 thereby is recharged to thenegative battery voltage in a very short length of time as compared tothe time period following closure of the contacts 199, 214, to reach theDarlington turn on voltage.

This way, a long delay time may be achieved with a small capacitor 228and a very fast reset time is also available.

This fast reset time is due to the switching action of the transistor232 and the relatively low resistance value of the resistor 260. Thelong delay time is due to the large voltage swing which the capacitormust undergo before the Darlington turn on voltage is reached and thelarge value of resistor 226. The large swing of voltage is due to thefact that the capacitor 228 is initially charged, at the base of theDarlington amplifier 206, negative with respect to ground.

The primary function of the unidirectional current diodes 224, 238 inthe circuit is to insure that only one component (either the solenoidvalve or the electric motor driven air pump) is turned on when theDarlington pair is turned on.

When the switch 214 is closed by a large load increase on the vehicle aperiod of time elapses until the Darlington turn on voltage is reached.When this occurs the solenoid valve 74 opens and, as shown in FIG. I,high-pressure fluid from within the tank 54 passes through the conduit44 into both of the auxiliary load supporting devices l2, 14 therebyproducing a resultant uplifting force on the chassis of the vehicle thatsupplements that of the primary coil spring to return the vehiclechassis to its desired level operating position.

When the vehicle is unloaded the motor controlled switch 196 is closed,and after it remains closed for the same specified length of time, thecompressor 58 is actuated. However, the compressor motor current doesnot pass through the Darlington amplifier 206. The amplifier does carrycurrent through the energization circuit for the coil 200 which causesan armature 262 of the relay 254 to be pulled in a direction to closethe contacts 262 of the relay 254 to complete the energization circuitfor the motor 56. This arrangement avoids the need for using a largesolid state switching device capable of carrying the energizationcurrent of the pump motor which is in the order of 28 amperes.

In one working embodiment of the above-described circuit, the electricaland mechanical components have the following ratings:

ln the aforementioned circuit, the time delay function provided by theRC circuit defined by resistor 226 and capacitor 228 is 5 seconds.

Another feature of this arrangement is that the Darlington Amplifier 206can be triggered in a range from I to L6 volts depending upon thetemperature condition of operation, even with the charging sourcevarying in the range from l0 to l5 volts.

Another advantage is that the ratio of the reset bias resistor 260 tothe timing circuit resistor 226 is I00 to 200 which allows the capacitorto be recharged to an initial negative battery voltage at the base ofthe Darlington amplifier 206 in a much shorter period of time than a tensecond timing period that it takes to charge the Darlington amplifier206 to a turn on voltage through the timing circuit defined by resistor226, capacitor 228 and the conductive transistor 232. In this way a longtime delay can be achieved with a small low cost capacitor and a fastreset time is available because of the switching action of the low costtransistor 232.

Because of this ratio the charging time to turn on the Darlingtonamplifier 206 is in the order of ten seconds and the reset time is inthe order of A second which in effect is instantaneous insofar as theoperational characteristics of the mechanical leveling system isconcerned.

While the embodiments of the present invention, as herein disclosed,constitute a preferred form, it is to be understood that other formsmight be adopted.

We claim:

1. An automatic vehicle leveling system comprising pressurizableauxiliary spring means for maintaining a predetermined heightrelationship between the spning and the unsprung mass of a vehicle, atank including an outlet therefrom. conduit means for communicating theoutlet with said spring means, solenoid operated valve means including afirst electrically energizable component for controlling flow ofpressurized fluid from said tank through said outlet, a compressorwithin said tank including an inlet, check valve means communicatingsaid compressor inlet with said conduit means, said check valve meansblocking flow of fluid from said inlet to said conduit means, meansincluding a second electrically energizable component for operating saidcompressor, said compressor including an outlet directly incommunication with the interior of said tank for pressurizing said tankwhen said compressor is operated, an undamped height sensor switchresponsive to the height relationship between the sprung and unsprungmasses having a first operative position for connecting one of saidelectrically energizable components to a power source and a secondoperating position for connecting the other of said components to apower source, circuit means electrically connected to each of saidenergizable components for controlling energization thereof when saidheight sensor is in either its first or second position, said circuitmeans including time delay means for preventing operation of saidcomponents during a momentary movement of said height sensor into saidfirst and second positions, said time delay means being responsive to apredetermined sustained closure of said undamped sensor to conditionsaid circuit means to energize said first or second electricalcomponents.

2. In an automatic vehicle leveling system of the type including anauxiliary fluid spring between the sprung and the unsprung mass which isselectively pressurized under the con trol of an undamped height sensorswitch for selectively energizing an electric motor driven compressorthe combination of; first and second electrically energizablecomponents, one of said components being operated during a pump-up phaseof operation and the other of said components being operated during anexhaust phase of operation, means for electrically connecting each ofsaid components to a power source including a switching device, meansfor directing a signal from the undamped height sensor switch when thevehicle is above or below a predetermined height relationship, timedelay means responsive to said signal following a predetermined periodof time to condition said switching device to energize one of saidelectrical components to produce either said pump-up or exhaust phase ofoperation, and means operative to reset said time delay means when asignal from the height sensor is of a duration less than that requiredto condition said switching device for energiration of either said firstor second electrical components.

3. An automatic leveling system for a vehicle having a sprung and anunsprung mass comprising; a pair of spaced apart auxiliary pressurizablesprings interposed between the sprung and the unsprung mas of a vehiclefor maintaining a predetermined height therebetween, an undamped heightsensor switch for sensing the position of the sprung mass with respectto the unsprung mass, a pressure tank, an electric motor located withinsaid tank, a compressor driven by said electric motor including an inletand an outlet, said outlet being in direct communication with theinterior of said tank, an integral valve assembly having a check valveand a solenoid operated valve therein, means communicating said checkvalve with said compressor inlet, said valve assembly including a cover,a crossover passageway in said assembly communicating said solenoidoperated valve with said check valve, a common conduit connected to saidcrossover passageway and to said springs for varying the pressure leveltherein, said undamped height sensor switch including first means forconditioning said solenoid operated valve to communicate the interior ofsaid storage tank with said crossover passageway during a pump-up phaseof operation, said height sensor switch including second means operativeto energize said electric motor to operate said compressor to exhaustfluid from said springs through said common conduit and said check valveto said compressor for discharge into said tank during a pumpdown phaseof operation, and circuit means electrically interposed between saidundamped height sensor switch and said electrically energizable solenoidoperated valve and electric drive motor for delaying operation of saidvalve or motor in response to transient movements of the sprung massabove or below a predetermined height relationship with respect to theunsprung mass.

4. A combination valve assembly for use in an automatic leveling systemof the type including a pressure tank for supplying fluid spring means,a housing having an annular flange adapted to be fit through an openingin the pressure storage tank for the leveling system in sealingrelationship therewith, a header on said housing located exteriorly ofsaid tank and a skirt located interiorly thereof, said header includingmeans for charging said tank to a predetermined pressure level, saidheader further including a fitting adapted to be connected to a commonconduit for exhaust and pump up of fluid spring means, a crossoverpassageway in said header connected to said fitting, a first passagewayfrom said crossover, a second passageway from said crossover, solenoidvalve means for blocking said first crossover to control communicationbetween the interior of said tank and said fitting, a one way checkvalve mechanism for controlling flow of fluid through said secondpassageway during an exhaust phase of operation, said check valveincluding a valve seat around said second passageway, a valving element,and spring means for maintaining said check valve normally closedagainst said seat to prevent bacltflow of fluid through said secondpassageway into said conduit.

5. A combination valve and electronic control assembly for locationwithin a pressurized storage tank comprising; a housing having anelongated skirt located within said tank, an annular flange on saidhousing including means for sealing the opening through said annulartank, an outlet fitting from said housing, a first passageway incommunication with said outlet, second and third passagewaysintersecting said first passageway, said second passageway including avalve seat therein, solenoid operated valve means maintained normallyclosed against said seat for blocking communication between said tankinterior and said first passageway, said solenoid valve means includingan electrically energizable coil, an armature stem located centrally ofsaid coil, is s eeve bearing within said coil for slidably supportingsaid armature stem for reciprocal movement with respect to said coil,said coil and said sleeve defining a flow passageway from said tankinterior, spring means for maintaining said armature in a closedrelationship with respect to said seat, said coil when energized causingsaid stem to move downwardly against said spring to open said passagewayduring a pump-up phase of operation, said valve assembly furtherincluding a suction inlet, a one way check valve for blocking fluid flowfrom said suction inlet into said second passageway to preventhighpressure fluid leakage across a compressor through the inlet thereoffrom the pressu rized tank.

1. An automatic vehicle leveling system comprising pressurizableauxiliary spring means for maintaining a predetermined heightrelationship between the sprung and the unsprung mass of a vehicle, atank including an outlet therefrom, conduit means for communicating theoutlet with said spring means, solenoid operated valve means including afirst electrically energizable component for controlling flow oFpressurized fluid from said tank through said outlet, a compressorwithin said tank including an inlet, check valve means communicatingsaid compressor inlet with said conduit means, said check valve meansblocking flow of fluid from said inlet to said conduit means, meansincluding a second electrically energizable component for operating saidcompressor, said compressor including an outlet directly incommunication with the interior of said tank for pressurizing said tankwhen said compressor is operated, an undamped height sensor switchresponsive to the height relationship between the sprung and unsprungmasses having a first operative position for connecting one of saidelectrically energizable components to a power source and a secondoperating position for connecting the other of said components to apower source, circuit means electrically connected to each of saidenergizable components for controlling energization thereof when saidheight sensor is in either its first or second position, said circuitmeans including time delay means for preventing operation of saidcomponents during a momentary movement of said height sensor into saidfirst and second positions, said time delay means being responsive to apredetermined sustained closure of said undamped sensor to conditionsaid circuit means to energize said first or second electricalcomponents.
 2. In an automatic vehicle leveling system of the typeincluding an auxiliary fluid spring between the sprung and the unsprungmass which is selectively pressurized under the control of an undampedheight sensor switch for selectively energizing an electric motor drivencompressor the combination of; first and second electrically energizablecomponents, one of said components being operated during a pump-up phaseof operation and the other of said components being operated during anexhaust phase of operation, means for electrically connecting each ofsaid components to a power source including a switching device, meansfor directing a signal from the undamped height sensor switch when thevehicle is above or below a predetermined height relationship, timedelay means responsive to said signal following a predetermined periodof time to condition said switching device to energize one of saidelectrical components to produce either said pump-up or exhaust phase ofoperation, and means operative to reset said time delay means when asignal from the height sensor is of a duration less than that requiredto condition said switching device for energization of either said firstor second electrical components.
 3. An automatic leveling system for avehicle having a sprung and an unsprung mass comprising; a pair ofspaced apart auxiliary pressurizable springs interposed between thesprung and the unsprung mass of a vehicle for maintaining apredetermined height therebetween, an undamped height sensor switch forsensing the position of the sprung mass with respect to the unsprungmass, a pressure tank, an electric motor located within said tank, acompressor driven by said electric motor including an inlet and anoutlet, said outlet being in direct communication with the interior ofsaid tank, an integral valve assembly having a check valve and asolenoid operated valve therein, means communicating said check valvewith said compressor inlet, said valve assembly including a cover, acrossover passageway in said assembly communicating said solenoidoperated valve with said check valve, a common conduit connected to saidcrossover passageway and to said springs for varying the pressure leveltherein, said undamped height sensor switch including first means forconditioning said solenoid operated valve to communicate the interior ofsaid storage tank with said crossover passageway during a pump-up phaseof operation, said height sensor switch including second means operativeto energize said electric motor to operate said compressor to exhaustfluid from said springs through said common conduit and said check valveto said compressOr for discharge into said tank during a pumpdown phaseof operation, and circuit means electrically interposed between saidundamped height sensor switch and said electrically energizable solenoidoperated valve and electric drive motor for delaying operation of saidvalve or motor in response to transient movements of the sprung massabove or below a predetermined height relationship with respect to theunsprung mass.
 4. A combination valve assembly for use in an automaticleveling system of the type including a pressure tank for supplyingfluid spring means, a housing having an annular flange adapted to be fitthrough an opening in the pressure storage tank for the leveling systemin sealing relationship therewith, a header on said housing locatedexteriorly of said tank and a skirt located interiorly thereof, saidheader including means for charging said tank to a predeterminedpressure level, said header further including a fitting adapted to beconnected to a common conduit for exhaust and pump up of fluid springmeans, a crossover passageway in said header connected to said fitting,a first passageway from said crossover, a second passageway from saidcrossover, solenoid valve means for blocking said first crossover tocontrol communication between the interior of said tank and saidfitting, a one way check valve mechanism for controlling flow of fluidthrough said second passageway during an exhaust phase of operation,said check valve including a valve seat around said second passageway, avalving element, and spring means for maintaining said check valvenormally closed against said seat to prevent backflow of fluid throughsaid second passageway into said conduit.
 5. A combination valve andelectronic control assembly for location within a pressurized storagetank comprising; a housing having an elongated skirt located within saidtank, an annular flange on said housing including means for sealing theopening through said annular tank, an outlet fitting from said housing,a first passageway in communication with said outlet, second and thirdpassageways intersecting said first passageway, said second passagewayincluding a valve seat therein, solenoid operated valve means maintainednormally closed against said seat for blocking communication betweensaid tank interior and said first passageway, said solenoid valve meansincluding an electrically energizable coil, an armature stem locatedcentrally of said coil, a sleeve bearing within said coil for slidablysupporting said armature stem for reciprocal movement with respect tosaid coil, said coil and said sleeve defining a flow passageway fromsaid tank interior, spring means for maintaining said armature in aclosed relationship with respect to said seat, said coil when energizedcausing said stem to move downwardly against said spring to open saidpassageway during a pump-up phase of operation, said valve assemblyfurther including a suction inlet, a one way check valve for blockingfluid flow from said suction inlet into said second passageway toprevent high-pressure fluid leakage across a compressor through theinlet thereof from the pressurized tank.